Search PubMed⌕ Search

Biomedical subjects

T Nishimura

Publications and source records attributed to T Nishimura.

At least 1,153 records · Page 64Linked to original sources
PubMed1987

Paratropomyosin, a new myofibrillar protein, weakens rigor linkages formed between actin and myosin.

We have used an enzymatic technique to determine the weakening effect of paratropomyosin, a new myofibrillar protein, on rigor linkages formed between actin and myosin, and to clarify the distinct function of paratropomyosin, as to that of tropomyosin. Paratropomyosin inhibited the Mg-ATPase activity and enhanced the K-ATPase activity of reconstituted actomyosin stoichiometrically, and its maximal binding to actin was estimated to occur at a molar ratio of 1: 12.5. Paratropomyosin also inhibited the myofibrillar Mg-ATPase activity by 49% and enhanced the myofibrillar K-ATPase activity to 126%, while tropomyosin had no effect on these ATPases. These results indicate that paratropomyosin is able to bind to thin filaments of myofibrils, because the binding site for paratropomyosin on F-actin is different from that for tropomyosin, and that, due to its greater affinity for the myosin binding site on actin, paratropomyosin competes for the binding site and helps weaken rigor linkages.

Actins↗
PubMed1987

Left and right ventricular function after streptokinase reperfusion: assessment by gated blood pool scans.

Twenty-three patients with acute anterior or inferior myocardial infarction (AMI, IMI) were investigated by gated blood pool scans at a mean 4.9 h after reperfusion and 10 days later. Eighteen (78%) successful reperfusion cases were divided into two groups; reperfusion in less than 4 h (Rp less than 4 h, n = 9) and reperfusion in more than 4 h (Rp greater than 4 h, n = 9) from the onset of chest pain. As control group, gated blood pool scans were also performed in the early hours following infarction in an additional 42 patients who received conventional treatments. Rp less than 4 h demonstrated significant improvement of mean LVEF in AMI (from 39.5 +/- 3.3 to 50.3 +/- 3.1%, p less than 0.01) and IMI (from 54.6 +/- 4.3 to 60.4 +/- 5.8%, p less than 0.01). Improvement of initially abnormal segments was noticed in 68% of AMI and 65% of IMI by quantitative wall motion analysis, while Rp greater than 4 h showed only slight improvement of LVEF and regional wall motion compared to Rp less than 4 h. On the other hand, the control group showed no significant change in left ventricular performance and regional wall motion. In patients with AMI, RVEF remained within normal range. In IMI, whether reperfused or not, the RVEF showed moderate improvement. In conclusion, these studies indicated that the time of reperfusion and location of infarction may influence functional recovery after streptokinase reperfusion.

Adult↗
PubMed1987

The bactericidal mechanisms of polymorphonuclear leukocytes against Bacteroides fragilis: significance of the oxygen-dependent system.

The mechanism by which polymorphonuclear leukocytes (PMNs) kill ingested Bacteroides fragilis was examined using PMNs from patients with chronic granulomatous disease (CGD) which is an inherited disease characterized by the defect of their PMNs in oxygen-radical generation. The phagocytosis of B. fragilis by PMNs from CGD patients was comparable to that by normal PMNs. Although CGD cells killed B. fragilis to some extent, they did so less effectively than the normal PMNS. B. fragilis was killed by a xanthine oxidase system that generates oxygen radicals. When PMNs were incubated with opsonized B. fragilis, B. fragilis triggered the release of O2- and H2O2 from normal PMNs. Thus, normal PMNs appear to kill B. fragilis by both oxygen-dependent and oxygen-independent mechanisms.

Bacteroides fragilis↗
PubMed1987

Encephalocele, polycystic kidneys, and polydactyly with other defects. A necropsy case of Meckel syndrome and a review of literature.

Meckel syndrome, which is diagnosed by 2 of 3 main congenital malformations such as a occipital encephalocele, polycystic kidneys, and polydactyly, is an autosomally inherited recessive disease. We have experienced a case of Meckel syndrome and performed necropsy. Necropsy findings revealed multiple congenital malformations with occipital meningo-encephalocele and agenesis of the cerebellum, 6 digits on the hands and feet, polycystic kidneys. The criteria of Meckel syndrome is still unclear. We propose that the diagnosis of this syndrome may be accompanied by the presence of all triad of main malformations. Ninety four cases satisfying this criteria have been reported in the world literature. Several discussion were made from a review of the literature.

Abnormalities, Multiple↗
PubMed1987

Histaminergic neuromodulation of the release of vasopressin.

In an attempt to clarify the nature of histaminergic neuromodulation of the vasopressinergic system, several studies under different experimental paradigms were carried out. L-Histidine loads (8 mmol/kg, i.p.) induced a marked increase in histamine (HA) in the anterior (AHR) and posterior (PHR) hypothalamic regions, the median eminence (ME) and adenohypophysis (Ah) with no apparent effect on the concentration of HA in the neurohypophysis (Nh), as measured by high-performance liquid chromatography. These findings correlated with decreases in vasopressin (VP) levels in the AHR and ME, accompanied by increases of the neuropeptide in the PHR and Ah. Intraperitoneal injections of HA (6 mumol/kg), resulted in a significant (p less than 0.005) rise in VP levels in the PHR, ME and Ah. HA induced an elevation of VP in the prefrontal cortex (PFC) from 6.23 +/- 2.02 to 43 +/- 4.05 microU/mg, as well as a 60% reduction in neurohypophyseal VP. These HA-induced VP responses were abolished by both mepyramine (3 mumol/kg) and famotidine (4 mumol/kg) in the PHR and PFC. Mepyramine suppressed the HA-induced VP response in the Ah and enhanced it in the Nh, while famotidine did the opposite. When alpha-fluoromethylhistidine (FMH), an irreversible inhibitor of histidine decarboxylase, was administered at doses of 100 mg/kg/day (i.p.), hypothalamic HA levels fell by 40-45% after 1 h, by 50% after 3 h, and by 65-80% after 24 h in adrenalectomized rats. In the same conditions, but after a week of treatment with FMH, the VP response to adrenalectomy was clearly impaired.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1987

Juvenile retinal detachment.

The features and prognoses of 802 cases (908 eyes) of retinal detachment from 8 months to 19 years of age were studied with the patients divided into three age groups: 65 eyes in group I (0-9), 259 eyes in group II (10-14), and 584 eyes in group III (15-19). Eyes in group I were different from the others in many respects. In group I, traumatic detachments, preoperative complications, four-quadrant detachments, and eyes with undetected breaks were more frequent, and the prognosis was worse than in the other groups. Holes with lattice degenerations were most frequent in group III eyes having no history of trauma. Group III resembled adult retinal detachment and group II was thought to be the transitional type.

Adolescent↗
PubMed1987

Tardive dyskinesia and neuroleptic-induced parkinsonism in Japan.

The authors studied neuroleptic drug response in 126 inpatients in Japan. They found similar prevalences and risk factors of tardive dyskinesia and neuroleptic-induced parkinsonism in Japan and the West, despite cross-cultural differences in psychiatric practice.

Age Factors↗
PubMed1987

31P in-vivo spectroscopic study by high-field whole-body MR system--an application to a case with arteriosclerosis obliterans.

31P in-vivo spectroscopy was performed by a 1.5-tesla whole-body MR system. The 31P spectrum for the calf muscle in a patient with arteriosclerosis obliterans having intermittent claudication was obtained every two minutes. When the spectrum after the workload was compared with that at rest, an increase in inorganic phosphate (Pi) and a decrease in phosphocreatine (PCr) were observed, resulting in a strong decrease in the PCr/Pi ratio. This method can measure the ischemic and recovery stages of energy metabolism in skeletal muscle noninvasively and continuously in addition to magnetic resonance imaging.

Aged↗
PubMed1987

Differentiation of myocardial ischemia and left ventricular aneurysm in the genesis of exercise-induced ST-T changes in previous anterior myocardial infarction.

We attempted to differentiate between myocardial ischemia and left ventricular asynergy as the underlying mechanisms of exercise-induced ST-segment elevation in patients with previous myocardial infarction (MI). Sixty patients with previous anterior MI, who underwent stress myocardial scintigraphy (SMS) and coronary angiography (CAG), which revealed a single vessel disease of the left anterior descending artery, were entered in this study. SMS and CAG were performed within 3 months of MI onset, and SMS and ECG were quantitatively analyzed. T wave changes to a complete upright position with concomitant ST-segment elevation (T-dominant ST-elevation) was seen in 56% of the patients with post-MI angina pectoris (N = 16) and in 50% of those with significant redistribution in SMS (n = 20). On the other hand, ST-segment elevation without T wave reversion (ST-dominant ST-elevation) was seen in 43% of patients with severe LV asynergy (akinesis and dyskinesis, n = 39) and in 50% of those with severe scintigraphic defect in delayed images (relative thallium uptake less than or equal to 40%, n = 10). When these findings were combined, T-dominant ST-elevation had sensitivity and specificity of 54% and 78%, respectively, for the diagnosis of myocardial ischemia, while the corresponding values for ST-dominant ST-elevation were 44% and 100%, for the diagnosis of severe ventricular asynergy. We conclude that the two underlying mechanisms, ischemia and asynergy, may produce different changes in ST-T shape in patients with previous myocardial infarction.

Adult↗
PubMed1987

Time- and dose-dependent responses of brain histamine to intracerebroventricular and intraperitoneal administrations of growth hormone-releasing factor (GRF1-44).

Changes in the level of histamine (HA) in rat brain induced by intracerebroventricular (i.c.v.) and intraperitoneal (i.p.) administrations of growth hormone-releasing factor (GRF1-44) were studied. HA was determined by high-performance liquid chromatography (HPLC) in the anterior hypothalamic region, posterior hypothalamic region, median eminence, adenohypophysis, neurohypophysis, hippocampus and prefrontal cortex. GRF1-44 (1-10 micrograms, i.c.v.) induced significant time- and dose-dependent increases in the concentration of HA in the hypothalamo-hypophyseal system and time-dependent decrease of HA in the hippocampus. In contrast, after i.p. administration of GRF1-44 (10 micrograms) the level of HA in the hypothalamus tended to decrease but the total amount of H-1 receptors in the hypothalamo-hypophyseal system did not change. Circadian variations in the GRF-induced HA and growth hormone responses were also observed, responses being lower in the evening than in the morning. It is concluded that GRF interacts with HA at the central level to optimize the function of the somatotropinergic system.

Animals↗
PubMed1987

Somatostatin-induced histamine response in the rat central nervous system.

The effects of somatostatin (SS-14) (0.1-10 micrograms, i.c.v.) on brain histamine (HA) in male Wistar rats were investigated. HA was measured by HPLC with a cation exchanger and an automated fluorometric detection system. SS-14 induced time- and dose-dependent changes in the levels of HA in the anterior hypothalamus, posterior hypothalamus, median eminence, adenohypophysis, hippocampus, and frontal cortex. In the anterior hypothalamus, posterior hypothalamus and hippocampus, SS-14 (1 microgram, i.c.v.) significantly (p less than 0.01) decreased the levels of HA from 5 to 30 min. This response was delayed by 5 min in the frontal cortex and adenohypophysis. Only in the neurohypophysis, SS-14 increased the concentration of HA 10 min after injection, but this response was not dose-related. These results seem to indicate that SS-14 influences neuronal HA probably modifying HA release, it leading to a decrease of the levels of the biogenic amine in specific areas of the brain. Since this effect is opposite to that developed by growth hormone-releasing factor (GRF) in identical conditions, HA seems to fulfil the criteria by which a neuroendocrine modulator should currently respond in a specific time- and dose-dependent manner to those neuropeptides which modulate. Therefore, HA is likely to play a key role as a neuromodulator of the somatotropinergic system in the rat.

Animals↗
PubMed1987

Orally active 1-(cyclohexyloxycarbonyloxy)alkyl ester prodrugs of cefotiam.

Orally active 1-(alkyl substituted cyclohexyloxycarbonyloxy)alkyl ester prodrugs (9b-h) of 7 beta-[2-(2-aminothiazol-4-yl)acetamido]-3- [[[1-(2-dimethylaminoethyl)-1H-tetrazol-5-yl]thio]-methyl]ceph+ ++-3- em-4-carboxylic acid (cefotiam, CTM) have been studied as well as the thia (9i) and aza (9j) analogs. These represent derivatives of the 1-(cyclohexylacetoxy)ethyl ester (2) of CTM. The syntheses and oral bioavailability (BA) in mice are described. Among them, the 1-(cyclohexyloxycarbonyloxy)butyl ester (9h) gave the highest BA, 93.5%; the esters having a cyclohexyloxy group in the ester moiety gave BAs of more than 75%, although the BA of the 1-(ethoxycarbonyloxy)ethyl ester (9a) was only 23.9%. The thia analog showed a moderate BA, 46%, but the aza analog, 9j, did not show a BA of CTM. These results indicate that the 1-(substituted cyclohexyloxycarbonyloxy)alkyl group was the suitable promoiety to improve the oral BA of CTM. Chiral 1-(alkoxycarbonyloxy)alkyl groups used as the ester moiety, gave an almost 1: 1 mixture of diastereoisomeric esters. These were tested as such. However, an experiment in which the separated isomers of the 1-(cyclohexyloxycarbonyloxy)ethyl ester (9d) were administered orally confirmed that both diastereoisomers gave identical BAs.

Administration, Oral↗